⁨⁨⁨أسئلة الخامسة جراحة رابعة دمياط (نيورو) ⁩⁩⁩

• This study guide covers peripheral nerve injuries of the lower limb, focusing on the lumbar and sacral plexuses.
• The content reviews the origin, branches, and clinical implications of nerve damage.

Lumbosacral plexus injury

• The lumbar plexus and sacral plexus are 2 plexuses which together form the lumbosacral plexus.
• It is connected through the anterior primary rami of L4

Lumbar Plexus

• Formed by the ventral rami of the first 4 lumbar nerves (L1,2,3,4).
• Lies within the psoas major muscle.
• The plexus divides into several cords.
• Cords combine and form the 6 major peripheral nerves.
• Nerves of the lumbar plexus serve the skin and the muscles of the lower abdominal wall, the thigh, and external genitals.

Branches of Lumbar Plexus

• Iliohypogastric nerve: T12-L1.
• Ilioinguinal nerve: T12- L1.
• Genitofemoral Nerve: L1,2.
• Lateral Cutaneous Femoral Nerve: L2,3.
• Obturator Nerve: L2,3,4.
• Femoral nerves L2,3,4.

Iliohypogastric Nerve

• Origin: T12-L1.
• Motor: Internal oblique and transverse abdominis muscles.
• Sensory: Skin over the suprapubic region.
• Injury: Abdominal surgery.

Ilioinguinal Nerve

• Origin: T12-L1.
• Motor: Internal oblique and transverse abdominis muscles.
• Sensory: Skin of external genitalia and the upper part of the medial aspect of the thigh.
• Injury: Abdominal surgery.

Genitofemoral Nerve

• Origin: L1,2.
• Motor: Cremasteric muscle and spermatic cord.
• Sensory: External genitalia (scrotum & labia).
• Injury: Laparoscopic surgery.

Lateral Femoral Cutaneous Nerve

• Origin: L2,3. Enters the thigh below the inguinal ligament
• Cause: Usually due to entrapment below the inguinal ligament (Meralgia parasthetica).
• Manifestation: Pain & numbness sensation on the anterior aspect of the thigh.
• Risk factors: (LFC) Lazy & Fat persons, Tight Clothes
• Injury: Usually due to entrapment of the lateral femoral cutaneous nerve of the thigh below the inguinal ligament (Meralgia parathetica)

Obturator Nerve

• Origin: Lumbar plexus anterior division of ventral rami L (1, 2, 3).
• Motor: Adductor longus, adductor brevis, gracilis, and pectineus (occasionally).
• Sensory: Sensory to subsartorial plexus.
• Post. division Motor: Adductor magnus (pubic part) and obturator externus

Obturator Nerve Injury

• Causes: Difficult delivery, pelvic surgery, pelvic tumor.
• Motor: Weakness of the adductor muscles of the thigh (except pectineus & pubic part of the adductor magnus).
• Sensory: Loss of sensation of a small area of the medial side of the thigh.
• Deformity: Weakness in adduction of the thigh.

Femoral Nerve

• Origin: Lumbar plexus (posterior division of ventral rami L1,2,3).
• Motor: Sartorius
  • Flexor of thigh
  • Extensor of leg
  • Medial rotation to leg
• Sensory: Intermediate & medial cutaneous nerve of the thigh.
• Motor: Quadriceps femoris.
• Sensory: Saphenous nerve and iliacus (in the abdomen) & pectineus.

Femoral Nerve Injury

• Causes: Stab wound or fracture of the hip bone.
• Motor: Paralysis of the extensors of the knee muscles, wasting of quadriceps femoris, and loss of knee reflex.
• Sensory: Loss of sensation over the front & medial side of the thigh, medial side of the leg, and medial side of the dorsum of the foot up to the root of the big toe.
• Deformity: Inability to extend the knee.

THE SACRAL PLEXUS

• Formed by the anterior rami of (S1, S2, S3 & S4)
• It is Located on the piriformis muscle, leaves the pelvis via the greater sciatic foramen

N.B

• Receives contributions from the lumbar spinal nerves L4 & L5 through the lumbosacral trunk
• The nerves innervate the pelvic muscles, organs and perineum, also enter the gluteal region of the lower limb, innervating the structures there.

Branches of Sacral Plexus

• Superior gluteal nerve: L4,5-S1
• Inferior gluteal nerve: L5-S1,2
• Sciatic nerve: L4,5-S1,2,3
  • Common peroneal nerve: L4-S2
  • Tibial nerve: L4-S3
• Posterior cutaneous nerve of the thigh: S1,2,3
• Pudendal nerve: S1,2,3.S4

Superior Gluteal Nerve

• Origin: Sacral plexus L4, L5, S1
• Supply: Gluteus minimus, gluteus medius, and tensor fascia lata
• Causes of Injury: Penetrating trauma, posterior hip dislocation, or false IM injection.
• Effect of Injury: Paralysis of the main abductors of the hip lead to Trendelenburg gait: positive Trendelenburg sign and compensated Trendelenburg.

Inferior Gluteal Nerve

• Origin: Sacral plexus (L5, S1, S2)
• Supply: Gluteus maximus (main extensor of the hip joint)
• Causes of Injury: Pelvic surgery.
• Effect of Injury: Inability to stand from a sitting position (failure of extension of the hip).

Sciatic Nerve (Flexors of the knee)

• Origin: Sacral plexus (L4, L5, S1, S2, S3)
• Course: Passes through Greater Sciatic Foramen (GSF) below the pyriformis

Branches

Tibial Nerve

• Motor Function: Muscles in the posterior compartment of the thigh, all hamstring muscles except the short head of biceps femoris, the ischial part of adductor magnus, and all the muscles in the posterior compartment of the leg & sole of the foot.
• Sensory Function: The skin of the posterolateral leg, lateral foot and the sole of the foot.

Common Peroneal Nerve

• Motor Function: Short head of biceps femoris, all muscles in the anterior & lateral compartments of the leg, and the extensor digitorum brevis.
• Sensory Function: The skin of the lateral leg and the dorsum of the foot.

Sciatic Nerve Injury

• Causes of Injury: False IM injection, pelvic fracture, stab wound to the thigh, posterior hip dislocation, or Pyriformis syndrome.
• Motor Effect of Injury: Paralysis of all hamstring muscles EXCEPT the short head of biceps femoris, paralysis of all muscles of the leg and foot, and weakness of knee flexion (not total loss - Sartorius & gracile).
• Sensory Effect of Injury: Loss of sensation in leg (EXCEPT area of saphenous nerve).
• Deformity: Foot drop, loss of inversion & eversion of the foot, and paralysis of all muscles of the leg and foot.

Common Peroneal Nerve

• Origin: The smaller of 2 terminal branches of sciatic nerve (L4,5-S1,2)
• Supply: (Extensors & Evertors of the foot) Superficial & deep peroneal nerve at the neck of the fibula.

Branches

• Motor: in popliteal fossa. Sural communicating, lateral cutaneous nerve of the calf.
  • at the neck of the fibula:
    • Superficial: Peroneus longus & brevis, medial & lateral terminal branches
    • Deep :Tibialis anterior, Extensor hallucis longus, Extensor digitorum longus, Peroneus tertius

Tibial Nerve

• Origin: The larger of the terminal branches of sciatic N (L4,5-S1,2,3)
• Supply: (Flexors & Invertors of the foot) Medial & lateral planter nerve.
• Motor: Gastrocnemius, Soleus, Plantaris, Popliteus, Flexor digitorum longus, Flexor hallucis longus, and Tibialis posterior (invertors).
• Sensory: Sural nerve

Injuries of Common Peroneal & Tibial Nerve

Cause

• Fracture neck fibula.
• Fracture of the upper part of the tibia
• Tarsal tunnel syndrome
• Jogger's foot

Motor

• Paralysis of the anterior muscles of the leg (Extensors)
• Paralysis of the lateral muscle of the leg (Evertors)
• Paralysis of all muscles of the back of the leg (planter flexors of foot)
• Paralysis of all muscles of the sole.

Effect

The patient drag the affected foot walking. The foot of the patient will tack the position of dorsiflexion & eversion. The patient will not be able to stand on his toe tips.

Sensory

• Loss of sensation front & anterolateral side of the leg dorsum of foot Interdigital clefts
• Loss of sensation 1st web space. Loss of sensation:
• The posterolateral side of the leg lateral side of the dorsum of the foot
• Heel of the foot
• Plantar aspect of the foot

Deformity

• Drop foot → high steppage gait
• Talipes equino-varus " club foot" Talipes calcanoeo-valgus.

FOOT DROP

• Inability to raise the front part of the food due to weakness or paralysis of the tabialis anterior muscle that lift the foot up.
• Usually result from injury to the peroneal nerve at any point of its course: - L4-5 disc herniation - lumbosacral plexus injury fracture pelvis - hip dislocation - Knee dislocation; nerve and artery - Established compartment syndrome
• High steppage gait : Raising the thigh up in exaggerated fashion while walking & the foot Treatment: Slaps down into the floor.

The posterior cutaneous N of thigh

• Origin: S1, S2, S3 Leaves the pelvis via the greater sciatic foramen, entering the gluteal region inferiorly to the piriformis muscle. Descends deep to the gluteus maximus and runs down the back of the thigh to the knee.
• Sensory Function: Skin on the posterior surface of the thigh & leg, and skin of the perineum.

Pudendal Nerve

• Origin: S2, S3, S4. This nerve leaves the pelvis via the greater sciatic foramen, then re-enters via the lesser sciatic foramen. Terminates by dividing into several branches.
• Motor Functions: Skeletal muscles in perineum, External urethral sphincter, External anal sphincter, and Levator ani.
• Sensory Functions: Skin of the penis & the clitoris, and most of the skin of the perineum.

NERVE ENtrapment SYNDROMES

Entrapment neuropathies

• Are a group of disorders of the peripheral nerves with are characterized by: pain and/or loss of function (motor and/or sensory) of the nerves as a result of chronic compression.

Common entrapment syndromes

• Carpal tunnel syndrome: " the most common”, Compression of the median nerve at the wrist

The Compression:

• The median nerve at the wrist
• Cubital tunnel syndrome: "the second most common", Caused by compression at the elbow.

Uncommon and rare entrapment neuropathies

• Ulnar nerve compression at the wrist (Guyon canal)
• Radial nerve in the proximal forearm
• Posterior interosseous nerve syndrome
• Suprascapular nerve entrapment
• Lateral femoral cutaneous nerve entrapment
• Common peroneal nerve entrapment

Tarsal tunnel syndrome:

Compression:

• Compression of the tibial nerve behind the medial malleolus.

Thoracic outlet syndrome:

• Entrapment of the lower trunk of the brachial plexus at the thoracic inlet

Carpal Tunnel Syndrome

• The compression of a compressive neuropathy of the median nerve at the level of the wrist.
• Affects 0.1-10% of general population.

Carpal Tunnel Syndrome Symptoms

• Numbness & tingling in radial 3½ digits.
• Clumsiness, and pain & paresthesia that awaken the patient at night.

Investigations

• Nerve conduction velocity (NCV): prolonged latencies (slowing) of NCV
• Electromyography

Carpal Tunnel Syndrome test symptoms

• The most sensitive test.
• Wrist volar flexion against gravity for ~60 sec produces - symptoms.
• Provocative tests are performed by tapping the median nerve over the volar carpal tunnel

Carpal Tunnel Syndrome Treatment

• Non operative (1st line of in early cases")

  • NSAIDS
  • Night splints
  • Activity modifications
  • Steroid injections.

• Operative

  • .Indication: failure of nonoperative treatment